function ZhiShu(a)
	y=1
	for i=2,a/2+1 do
		if(a%i==0) then
			y=0
			break
		end
	end
	return y			
end

io.write('2Dao N DeZhiShu   N=?')
N=io.read()
x=0
for i=1,	N do 
	y=ZhiShu(i)
	if(y==1) then
		x=x+1
		io.write('x' .. x .. '=' .. i .. '     ')
	end
end
	
